#!/bin/sh

usage () {
  echo "usage:" "$@"
  exit 127
}

die () {
  echo "$@"
  exit 128
}

if test $# -lt 2 || test $# -gt 3
then
  usage "$0 <repository> <new_workdir> [<branch>]"
fi

. "$__SHLIB__/common.sh"

orig_git=$1
new_workdir=$2
branch=$3

# want to make sure that what is pointed to has a .git directory ...
git_dir=$(cd "$orig_git" 2>/dev/null &&
  git rev-parse --git-dir 2>/dev/null) ||
  die "Not a git repository: \"$orig_git\""

case "$git_dir" in
.git)
  git_dir="$orig_git/.git"
  ;;
.)
  git_dir=$orig_git
  ;;
esac

# don't link to a configured bare repository
isbare=$(git --git-dir="$git_dir" config --bool --get core.bare)
if test ztrue = z$isbare
then
  die "\"$git_dir\" has core.bare set to true," \
    " remove from \"$git_dir/config\" to use $0"
fi

# don't link to a workdir
if test -h "$git_dir/config"
then
  die "\"$orig_git\" is a working directory only, please specify" \
    "a complete repository."
fi

# don't recreate a workdir over an existing repository
if test -e "$new_workdir"
then
  die "destination directory '$new_workdir' already exists."
fi

# make sure the links use full paths
git_dir=$(cd "$git_dir"; pwd)

# create the workdir
mkdir -p "$new_workdir/.git" || die "unable to create \"$new_workdir\"!"

# create the links to the original repo.  explicitly exclude index, HEAD and
# logs/HEAD from the list since they are purely related to the current working
# directory, and should not be shared.
for x in config refs logs/refs objects info hooks packed-refs remotes rr-cache svn
do
  case $x in
  */*)
    mkdir -p "$(dirname "$new_workdir/.git/$x")"
    ;;
  esac
  ln -s "$git_dir/$x" "$new_workdir/.git/$x"
done

# now setup the workdir
cd "$new_workdir"
# copy the HEAD from the original repository as a default branch
cp "$git_dir/HEAD" .git/HEAD
# checkout the branch (either the same as HEAD from the original repository, or
# the one that was asked for)
if [ -z "$branch" ]; then
  branch=$(basename "$new_workdir")
fi
git_branch_exist "$branch"
if [ "$RETVAL" -eq 1 ];
then
  git checkout -f "$branch"
else
  git checkout -f -b "$branch"
fi
